The present invention generally relates to electrochemical cells and, more particularly, to a beaded can for supporting the collector and seal assembly in an electrochemical cell, i.e., battery, and method of forming the same.
Conventional alkaline electrochemical cells generally include a steel cylindrical can having a positive electrode, commonly referred to as the cathode, which often comprises manganese dioxide as the active material. The electrochemical cell also includes a negative electrode, commonly referred to as the anode, which often comprises zinc powder as the active material. Conventional cells often employ a bobbin-type construction in which the anode is centrally located and is surrounded by a tubularly shaped cathode. A separator is generally located between the anode and the cathode, and an alkaline electrolyte solution simultaneously contacts the anode, the cathode, and the separator. A conductive current collector is typically inserted into the anode active material, and a seal assembly, which includes an annular polymeric, seal such as nylon, provides closure to the open end of the steel can to seal the active electrochemical materials in the can.
The conventional steel can has a closed bottom end, an open top end, and cylindrical side walls extending between the top and bottom ends. The open top end of the can typically has a flared or otherwise enlarged opening, and some cans have a continuous bead formed in the can's side walls at a location sufficient to support the collector and seal assembly. Conventional cells are generally sealed closed by disposing the annular polymeric seal in the open top end of the steel can so that the seal rests on top of the bead, and crimping the open top end of the can radially inward and over the outer periphery of the seal and an outer cover to compress the seal and outer cover against the bead. The bead therefore provides support for the can crimping process and also controls collector movement.
In conventional cell assemblies, the bead is formed in the can's side walls as an approximate U-shaped channel extending radially inward throughout a complete 360 degree rotation of the can, such that the bead is symmetric about the longitudinal axis of the can. In conventional cell assembly processes, the continuous bead is formed by rotating the can through a 360 degree rotation while, at the same time, forcibly forming the radially inward bead in the can wall with the use of rotary beading equipment. The conventional rotary beading equipment is generally costly and time-consuming to build, maintain, and use. Accordingly, it is therefore desirable to provide for a can that has a collector and seal assembly support for use in an electrochemical cell that offers reduced cost and is quicker to produce.